This study evaluated the repeatability of the Developmental Eye Movement Test (DEM) with three consecutive administrations on two separate visits to 181 children between the ages of 6 years and 11 years 11 months.
Children with visual acuity of ≥20/25, normal binocularity, and accommodation were administered three different versions of the DEM test. One to 4 weeks after the first administration of the DEM, the children were tested again using the same order for the three versions of the DEM. Measures of within- and between-session repeatability for the vertical-adjusted time, horizontal-adjusted time, ratio, and error scores were determined.
The within-session repeatability for vertical- and horizontal-adjusted time were good to excellent but were poor to good for ratio, and poor to fair for errors. The between-session intraclass correlation coefficients were fair to good for both the vertical and horizontal scores but poor for the ratio and error scores. The repeatability of the pass-fail diagnostic classification within a single session for each subject on test and retest was compared. The percentage of patients who remained in the same classification ranged from 71 to 100% for both vertical and horizontal scores. Wider variability was seen with the ratio and error scores showing between 47 and 100% of the children remaining classified as pass or fail with repeated administrations of the DEM. Such findings would suggest that children in this age range may show improvements in all four test scores without any intervention.
Although the DEM is widely used in optometric practice, the results of this study suggest that clinicians should be cautious about using the DEM test in isolation for reaching a diagnosis or monitoring the effectiveness of treatment for saccadic dysfunction.